For some applications, a pair of generators are connected in series to form a dual generator. This is done, for instance, where a maximum output voltage is required during certain periods of operation while a minimum output voltage is required at other times. For instance, it is not uncommon to require a maximum output voltage at the outset of an operation.
In such cases, two permanent magnet generators in series electrically can be utilized to accommodate the differences in required output voltage. This can be accomplished by controlling the phase of one of the two generators relative to the other generator to thereby control the output. Unfortunately, there has been no entirely satisfactory phase shifting device for this purpose.
Of course, one rotor-supporting shaft can be manually shifted relative to the other rotor-supporting shaft to accomplish the required phase shift. Depending upon the actual construction of the dual permanent magnet generator, however, this may require substantial time and effort or, perhaps, may not even be possible without reconstructing the generator particularly where the generator is designed for and normally operated in a selected phase relationship. Moreover, even with phase shifting devices specifically designed for dual permanent generators, the devices are generally oversized and less than entirely satisfactory.
While not specifically addressing the problems overcome by the present invention, Geiger U.S. Pat. No. 4,031,421, issued June 21, 1977, is directed to an electric generator. Also, LeGall U.S. Pat. No. 3,586,938, issued June 22, 1971, is directed to a phase-sensitive servomotor, DeRugeris U.S. Pat. No. 3,535,572, issued October 20, 1970 is directed to an alternator having rotatable magnetic field and armature structures, and Carlson U.S. Pat. No. 4,373,147, issued Feb. 8, 1983 is directed to a torque compensated electric motor, However, no one has successfully provided a phase shifting device for a dual permanent magnet generator having rotor-supporting shafts in drivingly interconnected relation.
The present invention is directed to overcoming the above stated problems and accomplishing the stated objects by providing such a phase shifting device.